Unexamined Japanese Patent Application Publication No. 2005-335,262 discloses a sheet processing apparatus for simply making a booklet by covering a sheet bundle comprised of a plurality of sheets with a cover in a U-shaped style, onto which images have been formed by an image forming apparatus, such as a copier and a printer.
The general outline of a technique for making a booklet will be described. Firstly, a plurality of sheets carrying the images are collected and aligned, being a sheet bundle. Then, adhesive agent is applied onto one surface of the sheet bundle. A coversheet is conveyed to a predetermined position, where the coversheet is attached to the surface of the sheet bundle onto which the adhesive agent has been coated. The plurality of sheets and the cover are formed into one body as a booklet, as described above.
FIG. 17 illustrates an example of booklets made by the sheet processing apparatus. FIG. 17(a) illustrates the situation where a cover S2 has not been folded and FIG. 17(b) illustrates the situation where the covers S2 has been folded. A booklet S3 is structured by a sheet bundle comprised of a plurality of sheets S1 and a cover S2. The booklet S3 is arranged so that the sheets S1 is covered by the cover S2 in a U-shaped style while symbol S3E is a spine. The positions of the side edge section S1E of the sheets S1 and the side edge section S2E of the cover S2 are matched in a final style of the booklet S3.
Unexamined Japanese Patent Application Publication No. 2003-25,755 discloses a sheet processing apparatus (a bookbinding apparatus) for automatically putting a coversheet so as to cover the cover of a booklet made by the sheet processing apparatus.
This sheet processing apparatus is arranged so that a folding roller folds a coversheet along the cover in response to the booklet. According to this sheet processing apparatus, since the booklet having a coversheet thereon is automatically outputted, a user does not need to put coversheet on the booklet.
According to the sheet processing apparatus (a bookbinding apparatus) disclosed by the Unexamined Japanese Patent Application Publication No. 2003-25,755 has an effect, from the viewpoint that a user can save time because the sheet processing apparatus automatically attach a coversheet onto the booklet. However, in case when the sheet processing apparatus automatically attaches the coversheet onto the booklet, it takes time to attach the coversheet onto the booklet. Thus, it is not efficient from the viewpoint of booklet productivity. Accordingly, there is an idea that a sheet processing apparatus is arranged to separately output a booklet and a coversheet without outputting a coversheet with a booklet from the viewpoint of the booklet productivity. In this case, since a user needs to put a coversheet onto the booklet, it is preferable that the sheet processing apparatus is arranged to form a fold-line on the coversheet before outputting it. The fold-line will be studied by using FIG. 18.
FIG. 18 illustrates the relationship between sheets S3 configuring a booklet, a cover S2 and a coversheet CV. FIG. 18(a) illustrates a situation where the cover S2 and the coversheet CV have not been folded, and FIG. 18(b) illustrates the situation where the coversheet CV has been open. In FIG. 18(a), in order to understand the relationship between the cover S2 and the coversheet CV, the cover S2 and the coversheet CV haven shifted each other. The dashed lines in FIG. 18(a) and FIG. 18(b) indicate the fold-lines on the coversheet CV. “X” in the FIG. 18(b) indicates the length of the coversheet CV, “A” denotes the thickness of the sheets S1 (which is also the width of the spine of the cover S2) and “B” denotes the lateral width of the sheet S1.
In case when the fold-line is not formed on an appropriate position of the coversheet, when the coversheet CV is attached on the booklet S3, since the edge of the booklet S3 and the fold-line of the coversheet CV do not match each other, appearance is not good. Further, when forming an image onto the coversheet CV, when the image formation position on the coversheet is not appropriate, there is a possibility that the image appears on the fold-line of the coversheet.